1. Field of the Invention
The present invention relates to subsea connectors and devices for limiting the bend of flexible pipes or umbilicals used with subsea connections. More particularly, the invention relates to subsea bend restrictors/limiters and/or bend stiffeners that are installable using remotely operated vehicles (ROVs).
2. Description of Related Art
Bend restrictors (or bend limiters) and/or bend stiffeners are used to inhibit overbending of flexible pipes or cable, flowline, and/or umbilical risers where the risers attach to fixed or floating structures such as, but not limited to, subsea riser bases, wellhead connections, pipeline end manifolds (PLEMs), and fixed or floating offshore platforms. The flexible pipes, flowlines, and/or umbilicals may be used, for example, to transport hydrocarbons or other fluids, to and from the surface. As an example, a bend restrictor/limiter may be used to inhibit overbending of an umbilical riser exiting an I- or J-tube on an offshore platform.
A bend restrictor/limiter may fit snugly over the riser and be tapered on the outside with a passage on the inside to allow the riser to pass through the bend restrictor/limiter. One end of the bend restrictor/limiter may be coupled to (e.g., secured or attached to) the riser base (e.g., the I- or J-tube) while the other end is freely moving. This structure allows the riser to move axially within the bend restrictor/limiter while lateral movement of the riser is inhibited by engaging the inside walls of the bend restrictor/limiter.
The riser may move laterally due to forces such as current or wave action. The stiffness provided by the bend restrictor/limiter limits the curvature of the riser and ensures that the curvature stays within a maximum curvature allowed by the design of the riser. This curvature limitation protects the riser from overbending and/or kinking.
In most subsea operations, the bend restrictor/limiter is installed with the riser at the time of offshore installation. The bend restrictor/limiter may be placed below the riser pullhead and inhibited from sliding down by, for example, a temporary hold back clamp installed on the riser. One end of the bend restrictor/limiter typically terminates in a flange that matches the flange on the structure (e.g., the flange on the end of the I- or J-tube).
During the riser pull-in and hang-off operations, a diver typically connects the flange on the bend restrictor/limiter to the flange on the structure. The diver may also remove the holdback clamp after connecting the flanges.
Using the diver to connect the bend restrictor/limiter has certain risks and dangers associated with people operating heavy machinery in a subsea environment. In addition, there are certain logistical, commercial, and operational risks associated with coordinating installation activity with diving activity. Diving activity and support associated with the diving activity may also be expensive and increase the costs of installation of the bend restrictor/limiter. Diver installation also may be slow and tedious, which may also increase costs and delay times for structure operation due to waiting for the diving operation to be completed.
Thus, there is a need for a subsea connector for bend restrictors/limiters that is installable without the need for using human divers. Specifically, a subsea connector for bend restrictors/limiters that is installable using automated systems such as, but not limited to, a remotely operated vehicle (ROV) may be advantageous. Having an ROV installable connector for bend restrictors/limiters would eliminate the need for diving operations and the associated risks and dangers to people (e.g., divers). The ROV installable connector for bend restrictors/limiters may also reduce logistical, commercial, and operational risks by eliminating the need to coordinate installation activity with diving activity. The ROV installable connector for bend restrictors/limiters may also reduce installation costs associated with diving activity and diving activity support. The ROV installable connector for bend restrictors/limiters may also improve the speed of operations and reduce costs by decreasing installation and connection time for the bend restrictor/limiter.